A zealot is someone who is very passionate about a cause or belief.
Simon the Zealot
In the Bible, this term is used to describe Simon, one of Jesus's twelve closest followers (Luke 6:15; Acts 1:13). This Simon is different from Simon Peter, who was also one of the twelve.
Matthew and Mark use the word "Cananaean" instead of zealot (Matthew 10:4; Mark 3:18). These words mean the same thing in different languages. They describe someone who is very eager to defend or support something. The word comes from the idea of "burning with strong feelings" or "wanting something very much" (Exodus 34:14; 2 Maccabees 4:2).
Jesus himself showed zeal (strong enthusiasm) when he cleared the temple of people who were misusing it. The Bible says he had "zeal for God's house" (John 2:17).
In the early Christian church, some believers were zealous for spiritual gifts, good works, and following God's law (Acts 21:20; 1 Corinthians 14:12; Titus 2:14). Paul, before he became a follower of Jesus, was very zealous for the traditions of his ancestors and for God (Acts 22:3; Galatians 1:14).
Simon the Zealot was known for his strong religious enthusiasm. This is how people could tell him apart from Simon Peter and the other followers of Jesus.
How the Zealot Movement Began
By the time Luke wrote his gospel, the title "Zealot" had come to mean something more specific. It referred to a group of people who were strongly against Roman rule over their land. This group had both religious and political goals.
This Zealot group may have started around AD 6, after the death of King Herod the Great. It was possibly founded by Judas the Galilean and Zadok the Pharisee. The Zealots were inspired by the Maccabees, who had fought against foreign rule many years earlier (1 Maccabees 2:15–28).
The Zealots were very devoted to following God's law (called the Torah). They believed that God was the only true king. They saw themselves as agents of God's judgment and salvation. They strongly opposed anything they saw as going against God or cooperating with Rome. The Zealots thought that the Messiah (God's chosen leader) would become their leader.
Zealots in Jewish History and Their Fight Against Rome
As tensions grew between Rome and Judea (the Jewish homeland), the Zealots became more militant. They saw their fight as a "holy war." While the Maccabees had fought to defend themselves, the Zealots became more aggressive.
Josephus, a Jewish historian, called them robbers and criminals (Antiquities 18.1.1–6; War 4.3.9), though he may have been biased against them. The Romans called them sicarii, which means "assassins." But their supporters would have called them patriotic fighters.
The Zealots played a big role in the revolt against Rome from AD 66 to 70. Their last stronghold was at a place called Masada. It fell to the Romans in AD 73, and the 960 Zealots there chose to die by suicide rather than be captured.
Simon the Zealot was probably part of this movement in its earlier days, around AD 30. It's less likely that other disciples like Judas Iscariot or the "sons of thunder" were Zealots (Mark 3:17). Judas the Galilean and even Paul were thought by some to be Zealots (Acts 5:37–38; 21:38).